The structural and functional properties of folded chromosomes in the yeast, Sccharomyces cerevisiae, will be studied in relation to two differentiative processes-- the cell cycle and the meiotic phase of the life cycle. These studies will include a sedimentation analysis of folded chromosomes isolated from cells at various stages of the cell cycle and from various meiotic stages. An essential component of these studies will be an analysis of folded chromosomes isolated from mutants which arrest at specific stages in the cell cycle or meiosis. In addition, the properties of various non-histone proteins from the folded chromosomes will be analyzed, particularly with regard to their DNA-binding properties and their effect on DNA conformation.